Accurate 'Scope Clock

The special 'scope clock that I bought
from David Forbes (Cathode Corner) has a 1 PPS BNC input on the rear.
Without this input the clock, like most clocks, is driven by an internal quartz oscillator. The 1
PPS feature allows the clock to be driven by a more accurate time source such as
a WWVB radio clock, a GPS satellite receiver, or an atomic clock.

The 'scope clock below is driven by the 1 PPS output of an
Agilent 5071A/001 Primary Frequency Standard (cesium atomic clock). This one is accurate to a
few nanoseconds a day.

Here, the 'scope clock is driven directly by the 1 PPS
output of a KVARZ CH1-75 Active
Hydrogen Maser. The stability of this maser is around 4x10-15 at 1 day
making this the most accurate 'scope clock on the planet.

To drive this
nixie clock from an atomic frequency standard I locked a synthesizer to the 5
MHz output of the atomic standard, set the synthesizer to generate a
low-level 60 Hz sine wave (and I mean, 60.000000000000 Hz), and then
amplified the signal with a bipolar DC
power supply to generate a high voltage "mains".

The nixie clock below is powered by a 60 Hz mains generated by
a HP 6827A bipolar power supply from a HP 3325B synthesizer from a
FTS/Datum 4065B/001 cesium standard. This one is accurate to a
few nanoseconds a day.

Here, the Nixie clock is driven by a KVARZ CH1-75 Active
Hydrogen Maser (5 MHz) through a HP 3325B synthesizer (60 Hz) through a HP
6827A bipolar power supply (100 VAC) to generate a 60 Hz mains. The
accuracy of the Nixie clock is thus locked to the accuracy of the hydrogen
maser. The stability of this maser is around 4x10-15 at 1 day
making this the most accurate Nixie clock on the planet. The 'scope clock
in the right is directly driven by the maser's 1 PPS output.

More photos of the atomic 60 Hz setup

HP 3325B with atomic standard as external reference

A 3 V rms sine wave is used to drive the 6827A

HP 6827A bipolar power supply/amplifier

Modified extension cord for synthesized mains

The 6827A peaks at about 100 VAC

Powering Nixie clock from synthesized mains

Accurate Flip Clock

And since one of my flip clocks runs from mains power, it's been added to the
list.